/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.expression.spel.support;

import java.beans.PropertyEditor;

import org.springframework.beans.BeansException;
import org.springframework.beans.SimpleTypeConverter;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.expression.TypeConverter;

/**
 * Copied from Spring Integration for purposes of reproducing
 * {@link Spr7538Tests}.
 */
class BeanFactoryTypeConverter implements TypeConverter, BeanFactoryAware {

    private SimpleTypeConverter delegate = new SimpleTypeConverter();

    private static ConversionService defaultConversionService;

    private ConversionService conversionService;

    public BeanFactoryTypeConverter() {
        synchronized (this) {
            if (defaultConversionService == null) {
                defaultConversionService = new DefaultConversionService();
            }
        }
        this.conversionService = defaultConversionService;
    }

    public BeanFactoryTypeConverter(ConversionService conversionService) {
        this.conversionService = conversionService;
    }

    public void setConversionService(ConversionService conversionService) {
        this.conversionService = conversionService;
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        if (beanFactory instanceof ConfigurableBeanFactory) {
            Object typeConverter = ((ConfigurableBeanFactory) beanFactory).getTypeConverter();
            if (typeConverter instanceof SimpleTypeConverter) {
                delegate = (SimpleTypeConverter) typeConverter;
            }
        }
    }

    public boolean canConvert(Class<?> sourceType, Class<?> targetType) {
        if (conversionService.canConvert(sourceType, targetType)) {
            return true;
        }
        if (!String.class.isAssignableFrom(sourceType) && !String.class.isAssignableFrom(targetType)) {
            // PropertyEditor cannot convert non-Strings
            return false;
        }
        if (!String.class.isAssignableFrom(sourceType)) {
            return delegate.findCustomEditor(sourceType, null) != null || delegate.getDefaultEditor(sourceType) != null;
        }
        return delegate.findCustomEditor(targetType, null) != null || delegate.getDefaultEditor(targetType) != null;
    }

    @Override
    public boolean canConvert(TypeDescriptor sourceTypeDescriptor, TypeDescriptor targetTypeDescriptor) {
        if (conversionService.canConvert(sourceTypeDescriptor, targetTypeDescriptor)) {
            return true;
        }
        // TODO: what does this mean? This method is not used in SpEL so probably ignorable?
        Class<?> sourceType = sourceTypeDescriptor.getObjectType();
        Class<?> targetType = targetTypeDescriptor.getObjectType();
        return canConvert(sourceType, targetType);
    }

    @Override
    public Object convertValue(Object value, TypeDescriptor sourceType, TypeDescriptor targetType) {
        if (targetType.getType() == Void.class || targetType.getType() == Void.TYPE) {
            return null;
        }
        if (conversionService.canConvert(sourceType, targetType)) {
            return conversionService.convert(value, sourceType, targetType);
        }
        if (!String.class.isAssignableFrom(sourceType.getType())) {
            PropertyEditor editor = delegate.findCustomEditor(sourceType.getType(), null);
            editor.setValue(value);
            return editor.getAsText();
        }
        return delegate.convertIfNecessary(value, targetType.getType());
    }

}
